In the past it has been known to cure a surface coating such as a coating of paint or ink by applying a vapour phase material to the coating, containing a catalyst which reacts with the coating to at least initiate the curing thereof. Such coatings may typically comprise synthetic polymers which are cured by the formation of long chains with cross-linking, accelerated by the catalyst contained in the vapour phase material.
In this specification the term "catalyst" will be used to refer to any suitable substance capable of use in a vapour phase for impingement onto a coating for accelerating and/or initiating curing of the coating.
Examples of methods for accelerating curing of the coatings of the type referred to above are to be found in the following patent specifications:
Australian 476,431 PA1 Australian 445,242 and U.S. equivalent U.S. Pat. No. 3,874,898 PA1 U.S. Pat. No. 2,892,734 (L. C. Hoffman) PA1 U.S. Pat. No. 2,657,151 (H. Gensel) PA1 U.S. Pat. No. 4,294,021 (J. O. Turnbull et al.) PA1 U.S. Pat. No. 3,851,402 (J. O. Turnbull et al.) PA1 U.S. Pat. No. 4,331,782 (G. L. Linden) PA1 U.S. Pat No. 2,810,662 (H. L. Barnebey) PA1 U.S. Pat. No. 3,874,948 (S. S. Kertel) PA1 U.S. Pat. No. 4,343,924 (G. L. Linden) PA1 U.S. Pat. No. 4,343,839 (J. R. Blegen)
The range of coatings with which the present invention is concerned is not restricted to but includes by way of example paint-like coatings such as urethane-resinous hybrid based paints, and printing inks.
It is a disadvantage of the curing of surface coatings by the application of vapour phase materials containing a catalyst, that while the coating so "cured" is nominally touch-dry after the application of the vapour phase material, the sub-surface layers of the coating may not yet be fully cured and a considerable time is necessary for a full cure of the surface coating. This time may delay further handling or packaging, etc., of the article to which the surface coating has been applied and results in inconvenience or delays which may be expensive in a manufacturing situation.
It is therefore an object of the present invention to provide a method of and apparatus for curing a coating on a substrate which will obviate or minimise the foregoing disadvantage in a simple yet effective manner, or which will at least provide the public with a useful choice.